How often do you clean your pot??
Haven't felt or seen a need to since I threw Marvacrap in the trash. How badly & how thick that stuff will cake rock hard on the sides of your pot has to be seen to be believed. Since using only sawdust as flux as the level in my pot goes down and I look at the sides of the pot I see only clean steel.
When smelting WW into ingots I flux at least twice for assurance the ingots are as clean as possible. When using (adding) these ingots to the casting pot it gets another good fluxing with sawdust.
My WW alloy is about as clean as practicle for bullet alloy from scrap. Not much to stick on the inside of the pot and need cleaning out. I also have no problems either bottom pouring or ladle casting. I guess if I started to get inclusions bottom pouring I would have to consider emptying it out and cleaning it but until that time . . . Sawdust only!
Rick